Formaldehyde is representative of aldehydes in the following description. Formaldehyde is a colorless, pungent-smelling gas, which can cause watery eyes, burning sensations in the eyes and throat, and difficulty in breathing when exposed to elevated levels, i.e. levels above 0.1 parts per million (ppm). Chronic exposure at lower concentration can also cause similar symptoms. High concentrations may trigger attacks in people with asthma. Some people can develop sensitivity to formaldehyde resulting in skin rashes, hives, etc. The International Agency on Cancer Research has classified formaldehyde as a known carcinogen.
Particularly indoors, the general population may be exposed to formaldehyde through its use in construction materials, wood products, textiles, home or office furnishing, paper, cosmetics, cigarette smoke, pharmaceuticals and indoor cleaning products. Formaldehyde levels are particularly high in new construction due to high emissions from new construction materials and interior furnishing. Thus, there is a need and desire to reduce or eliminate formaldehyde concentrations, particularly in closed spaces, such as offices, schools, factories, homes and healthcare facilities. It is further desired that a formaldehyde reducing substance, after reacting with formaldehyde, have little to no detrimental effect on the coating itself. For example, some existing formaldehyde reactive materials cause the coating to yellow initially or after exposure to the environmental substances such as NOx.
It is also worth noting that the requirements for including the formaldehyde reactive material in the coating are more stringent than when the formaldehyde reactive material is contained within the structure of the material as many of these detrimental effects can be masked deep within the structure of the material. Masking the detrimental effects is much more difficult when the reactive material is on or near the surface. The disclosed formaldehyde reducing surface coating also requires that the crystals of the formaldehyde reactive compound be fine, i.e. small in size, and well dispersed throughout the coating in order to obtain optimal formaldehyde reducing performance.